Fuel cell device

ABSTRACT

A fuel cell device comprises a fuel cell stack which is formed from a plurality of unit cells stacked one above the other in a stacking direction, each unit cell having one or more media channels and a membrane electrode assembly that comprises a cathode, an anode, and a membrane arranged between the cathode and the anode, and comprising a media duct running substantially parallel to the stacking direction. The media duct is connected or can be connected to the fuel cell stack to conduct a medium into or out of the media channels of the unit cells of the fuel cell stack substantially laterally to the stacking direction. The media duct is formed as a functional component or such a functional component is integrated therein, which is formed to pre-treat the medium before it enters the media channels or to post-treat the medium after it has exited the media channels.

BACKGROUND Technical Field

Embodiments of the invention relate to a fuel cell device comprising afuel cell stack which is formed from a plurality of unit cells stackedone above the other in a stacking direction which unit cell in each casehas one or more media channels and a membrane electrode assembly whichcomprises a cathode, an anode and a membrane arranged between thecathode and the anode, and a media duct running substantially parallelto the stacking direction, especially externally with respect to thestack, and which is connected or can be connected to the fuel cell stackso as to conduct a medium into or out of the media channels of the unitcells of the fuel cell stack substantially laterally to the stackingdirection.

Description of the Related Art

Fuel cell devices comprising media ducts externally with respect to thestack are known, for example, from US 2009/0226795 A1, JP 2005 071 959A, EP 1 836 739 B1 or DE 10 2010 011 206 A1. DE 103 15 601 A1 shows afuel cell device in which the media ducts are attached externally withrespect to the fuel cell stacks.

BRIEF SUMMARY

A fuel cell device as described herein has a compact design with limitedinstallation space.

The fuel cell device is characterized in that the media duct is formedas a functional component or such functional component is integratedtherein, which is designed to pre-treat the medium before it enters themedia channels, or to post-treat the medium after it has exited themedia channels. This means that the functional component for thetreatment of the medium is not arranged separately, but formed directlyin the media ducts or assigned to the media ducts. This results in asignificant saving in the space required by the fuel cell device. Inaddition, there is a reduced number of components.

The media ducts, the so-called external headers, are produced separatelyfrom the rest of the stack and are only connected to the stack after ithas been completed. The geometry of the functional component can thus bechosen independently of the geometry of the stack, while in addition thepossibility is opened up to choose the supply or discharge of the mediain the functional component regardless of the stacking direction.

The functional component may be selected from a group comprising ahumidifier, an ion exchanger, an ion trap, a particulate filter, an airfilter, and a water separator.

A simple to manufacture fuel cell device is characterized in thatseveral of the media ducts are provided that are formed as a first mediasupply for supplying air and as a first media discharge for dischargingthe at least partially consumed air, and that are formed as a secondmedia supply for supplying a fuel and as a second media discharge fordischarging the at least partially consumed fuel of the fuel cell stack.Thus, the two reaction media are conducted laterally along the fuel cellstack, i.e., externally with respect to the stack, in the media ducts,wherein they can enter into or exit from the unit cells of the fuel cellstack perpendicular to the stacking direction, that is to say,laterally.

In order to be able to adjust the moisture content in the fuel cellstack, the first media supply may be formed as a humidifier or such ahumidifier may be integrated therein.

In order not to output any contaminations to the environment, thepossibility is opened up that the first media discharge is formed as anair filter or such an air filter is integrated therein.

In order to also protect the fuel cell stack from contamination, it isuseful when the second media supply is formed as a particle filter orsuch a particle filter is integrated therein.

In order to collect condensate accumulating in the anode circuit, thesecond media discharge is formed as a water separator or such a waterseparator is integrated therein.

To conduct a coolant additionally externally with respect to the stackalong the fuel cell stack, and to conduct the coolant laterally into theunit cells or between two unit cells into the fuel cell stack, it isuseful to subdivide the media ducts also into a coolant supply and acoolant discharge.

This opens up the possibility that the coolant supply is formed as anion exchanger or such an ion exchanger is integrated therein. Thisensures that the coolant supplied to the fuel cell stack is electricallyneutral or below a critical conductivity value to avoid short circuitsor electrical charging of components.

In order to facilitate the assembly of the fuel cell device, the fuelcell stack, such as the unit cells, has flange receptacles which aredesigned to receive a respective duct flange of the media ducts, theduct flanges being connected directly to one another.

In this case, the duct flanges of the media duct are inserted in flangereceptacles of the fuel cell stack running substantially parallel to thestacking direction.

The duct flanges of the media ducts can be positioned laterally at thefuel cell stack with a predetermined stop at the fuel cell stack. Thisreduces the effort to assemble the media ducts at the right place. Inaddition, the assembly time for assembling the media ducts is minimizeddue to the flange receptacles formed on the fuel cell stack.

Such an assembly is also advantageous because a different material canbe selected for the media duct than for the unit cells or for thebipolar plates of the unit cells. Also, the number of the sealing trackscan be reduced that need to be made for sealing the media ducts. Thisalso reduces the production complexity.

It has been found to be useful when the flange receptacles of the fuelcell stack are formed as grooves running substantially parallel to thestacking direction. Such grooves are very easy to manufacture from amanufacturing point of view.

Furthermore, the media duct may be formed to be elastically resilient insuch a way that the duct flanges are held under a pre-load in the flangereceptacles. By such a pre-load the media ducts can be fixed in aself-locking manner during assembly on the fuel cell stack, wherein,additionally, a firmly bonded connection of the duct flanges to the fuelcell stack can be formed, such as with its flange receptacles, toestablish a fixed connection.

The restoring force may be directed outwards, because the pressuregenerated by the medium also causes an outwardly directed force on theduct flanges. Due to the summation of the force of the flowing mediumand the restoring force given by the elasticity, an even tighter andtherefore more secure connection of the media duct to the fuel cellstack is achieved.

An additional securing of the duct flanges within the flange receptaclescan be achieved in that the flange receptacles have an undercut runningsubstantially parallel to the stacking direction, which is formed insuch a way that a duct member formed or arranged at the one and/or theother duct flange can be received therein.

In order to strengthen the fixation of the duct flanges additionally,the duct member can be received in the undercut in an interlockingmanner.

In this context, it can also be useful if the duct member is formed froma different material than the duct flanges. For example, the duct membermay be formed of a material with adhesive properties, so thatoptionally, in addition to an interlocking connection - in addition,there is adhesion of the duct member within the undercut and thus afirmly bonded connection is additionally formed.

Because of the pressure prevailing in the media duct or in fuel cellstack caused by the medium conveyed therein, the connection of the mediaduct to the fuel cell stack is faced with the challenge of maintainingleakproofness. To meet this requirement, it has proven to be useful whenthe duct member is also formed of a sealing material.

In one configuration of the media duct, the duct flanges are connectedindirectly to each other via a duct crosspiece. In doing so, it can takethe shape of a U with the open end of the “U” facing the fuel cellstack, and thus the media are conducted from the outside to the fuelcell stack. Thus, the media flow within the media ducts substantiallyparallel to the stacking direction. They get into the fuel cell stack ina lateral or sideward direction (x-y direction) with respect to thestacking direction (z direction).

Alternatively, the duct flanges can also be connected directly to eachother, implementing a cross-sectionally C-shaped configuration of themedia ducts with an open end of the “C” towards the fuel cell stack.Here, too, the media flow within the media ducts substantially parallelto the stacking direction and get into the fuel cell stack in a lateralor sideward direction with respect to the stacking direction.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Further advantages, features and details emerge from the claims, thefollowing description and the drawings.

FIG. 1a shows a fuel cell device in a perspective view.

FIG. 1b shows another fuel cell device in a perspective view.

FIG. 2 shows a first bipolar plate of a unit cell in a plan view.

FIG. 3 shows section III-III of FIG. 2.

FIG. 4 shows the first bipolar plate of FIG. 2 with a composite layerapplied, shown in a plan view.

FIG. 5 shows section V-V of FIG. 4 with the components in anon-compressed state.

FIG. 6 shows the first bipolar plate of FIG. 4 with a fuel cell assemblyplaced thereon.

FIG. 7 shows section VII-VII of FIG. 6 with the components in anon-compressed state.

FIG. 8 shows the configuration of FIG. 6 with an applied connectinglayer.

FIG. 9 shows section IX-IX of FIG. 8 with the components in anon-compressed state.

FIG. 10 shows a unit cell of the fuel cell stack with a second bipolarplate, shown in a plan view.

FIG. 11 shows the second bipolar plate in a bottom view, i.e., in a viewof the surface of the second bipolar plate facing the membrane electrodeassembly.

FIG. 12 shows a fuel cell stack formed of several unit cells accordingto FIG. 10 in a perspective view.

FIG. 13 shows sectional view XIII-XIII of FIG. 10 by a plurality of unitcells stacked one above the other with the components in a compressedstate.

FIG. 14 shows sectional view XIV-XIV of FIG. 10 through a plurality ofunit cells stacked one above the other with the components in acompressed state.

FIG. 15 shows a cross section running perpendicular to the stackingdirection through the fuel cell stack of FIG. 1a with media ductsattached to it.

FIG. 16 shows a cross section running perpendicular to the stackingdirection through the fuel cell device of FIG. 1 b.

FIG. 17 shows a perspective detailed view of the fuel cell deviceaccording to FIG. 1 b.

FIG. 18 shows a detailed view of the flange receptacle and the end of aduct flange.

FIG. 19 shows another detailed view of the flange receptacle with ductflanges inserted therein.

DETAILED DESCRIPTION

It should be pointed out in advance that the dimensions, theproportions, and the scale of the illustrations shown are not fixed andcan vary. In the sectional illustrations, the individual layers areshown in such a way that it is possible to understand in which mutualposition and in which order the individual layers are stacked one abovethe other.

FIGS. 1a and 1 b, respectively, show a fuel cell device 1 comprising afuel cell stack 12. The fuel cell stack 12 is formed from a plurality ofunit cells 11 stacked one above the other in a stacking direction (zdirection). Each of the unit cells 11 has one or more media channels 8(FIG. 2) and a membrane electrode assembly 2 (FIG. 6). Each of themembrane electrode assemblies 2 in the unit cells 11 comprises acathode, an anode, and an ion-conductive membrane arranged between thecathode and the anode.

The fuel cell device 1 further comprises media ducts 22 running parallelto the stacking direction, which media ducts 22 are connected to thefuel cell stack 12 in such a way in order to conduct a mediumsubstantially laterally to the stacking direction into or out of themedia channels 8 of the unit cells 11 of the fuel cell stack 12. Thepresent fuel cell device 1 comprises several media ducts 22 for thispurpose, which are subdivided into a first media supply 22 a on a firstside of the fuel cell stack 12 for supplying a first reaction medium(e.g., oxygen or air) to the cathodes and into a first media discharge22 b on a second side of the fuel cell stack 12 opposite the first sidefor discharging the first reaction medium not consumed in the unit cells11. In addition, the media ducts 22 are subdivided into a secondreaction medium 22 c on a third side of the fuel cell stack 12 forsupplying a second reaction medium (e.g., fuel in the form of hydrogen)to the anodes and into a second media discharge 22 d on a fourth side ofthe fuel cell stack 12 opposite the third side for discharging thesecond reaction medium not consumed in the unit cells 11. Ultimately,the media ducts 22 are also subdivided into a coolant supply 22 e on thethird side of the fuel cell stack 12 for supplying a coolant (e.g.,liquid water) and into a coolant discharge 22 f on the fourth side ofthe fuel cell stack 12 for discharging of partially heated coolant.

It can be seen from FIGS. 1a and 1b that the media ducts 22 themselvesare functionalized, more precisely themselves are formed as a functionalcomponent 35. There is also the possibility that such a functionalcomponent 35 is integrated or introduced in cavities created by themedia ducts 22.

In the present case, the first media supply 22 a may be formed as ahumidifier 36 in order to adjust the moisture content in the fuel cellstack 12 by humidification of the supply air.

In the present case, the first media discharge 22 b may be formed as anair filter 37 in order to filter any contaminations.

In the present case, the second media supply 22 c may be formed as aparticle filter 38 in order to prevent a contamination of the fuel cellstack 12.

In the present case, the second media discharge 22 d may be formed as awater separator 39 in order to collect condensate accumulating in theanode circuit. Moreover, in the present case, the coolant supply 22 emay be formed as an ion exchanger 40 in order to lower the electricalconductivity of the coolant to be supplied to the fuel cell stack 12.

By way of example, the production or structure of the shown unit cells11 of the fuel cell stack 12 is explained below with reference to FIGS.2 to 11.

FIG. 2 shows a bipolar plate 7 of one of the unit cells 11. This firstbipolar plate 7 a has an inner active area 3, illustrated by dashedlines, and an outer edge area 5, illustrated by dashed lines. In theedge area 5, several media channels 8 are formed, which can besubdivided into the first media inlet channels 8 a, illustrated on theleft in the drawing, and the first media outlet channels 8 b,illustrated on the right in the drawing. In the present case, a pair offlange receptacles 26 surrounding the media channels 8 is formed,discussed in detail below. Further flange receptacles 26 are formed onthe long edges 17 a of the bipolar plate 7.

In the present case, five of the first media inlet channels 8 a and fiveof the first media outlet channels 8 b are formed in the first bipolarplate 7 a. Another number is possible. The first media inlet channels 8a are fluidly connected to the first media outlet channels 8 b via afirst flow field 13 a. Said flow field 13 a is located in the activearea 3 and may provide a reaction medium to an adjacent membraneelectrode assembly 2. In the example according to FIG. 2, the flow field13 a has several ducts or walls 14 for the uniform distribution of areaction medium over the surface of the membrane electrode assembly 2.However, it is also possible, to use other types of flow-fields 13 a,for example, those in which the flow of the reaction medium is conductedacross the area of the active surface in the form of a meander. Inaddition, the distance of the walls 14, the wallings or crosspieces canvary. Also, the depth of the channel formed by adjacent walls 14 can bedesigned to be different and vary.

As is apparent from FIG. 3, the section III-III of FIG. 2, a flow field13 c is formed also on the side the first bipolar plate 7 a facing awaywhich the membrane electrode assembly 2, which flow field 13 c allowsflow of another medium, for example, a coolant.

As shown in FIG. 4, a composite layer 15, such as a joining layer isapplied on the first bipolar plate 7 a in the edge area 5. Thiscomposite layer 15 is formed in several parts or has recesses 16 in thearea of the media channels 8 a, 8 b. The recesses 16 ensure that themedia inlet channels 8 a and the media outlet channels 8 b are notsealed and subsequently allow conducting media through them.

The composite layer 15 attached in the edge area 5 extends along thelong edge 17 a of the first bipolar plate 7 a, so that a flush finish tothe edge area 5 that is predetermined by the dimensions of the bipolarplate 7 is formed. Areas for the flange receptacles 26 also remain freeon the composite layer 15. This composite layer 15 is used to seal offthe active surface or the active area 3 from the environment, whereinthe choice of the material of the composite layer 15 is to be made toachieve this sealing function. In FIG. 5, the section V-V of FIG. 4, theflush finish of the composite layer 15 or the joining material with thebipolar plate 7 can be seen along its long edges 17 a. The sections ofthe composite layer 15 which are located at the short edges 17 b, arealso flush with the bipolar plate 7. The selected illustration of thecomposite layer 15 is an example. It can be configured to be muchthinner than the first bipolar plate 7 a.

In FIG. 6, a fuel cell assembly comprising a membrane electrode assembly2 was applied or placed onto the first bipolar plate 7 a of FIG. 4covered with the composite layer 15. The active area 3 is substantiallypredetermined by the dimensions of the membrane electrode assembly 2,which in turn is sketched in the figure by the inner dashed line. Theactive area 3 extends not only in a plane (x-y plane) but also in thestacking direction (z direction) which is oriented into or out of thepaper plane.

The active area 3 is the area in which the electrochemical reaction ofthe fuel cell formed by the membrane electrode assembly 2 takes place.In the electrochemical reaction, a fuel (e.g., hydrogen) is conducted tothe anode, where it is catalytically oxidized to form protons byreleasing electrons. These protons are transported to the cathodethrough the ion exchange membrane. The electrons released from the fuelcell flow via an electrical load, such as to an electric motor fordriving a vehicle, or to a battery. Then the electrons are conducted tothe cathode. At the cathode, the oxidation medium (e.g., oxygen or aircontaining oxygen) is reduced to form anions by the absorption ofelectrons, which react directly with the protons to form water.

In order to ensure that the fuel reaches the anode directly or that theoxidation medium reaches the cathode directly, a sealing structure 4 islaterally assigned to the membrane electrode assembly 2 (FIGS. 6, 8).The combination of the membrane electrode assembly 2 and the sealingstructure 4 in this case forms a common fuel cell assembly. Here, thesealing structure 4 comprises components that extend into the edge area5, or even protrude beyond the edge area 5. These components aretherefore arranged outside the active area 3. In other words, the edgearea 5 delimits the active area 3 in the radial or lateral direction orcircumferentially.

It can be seen in FIGS. 6 and 8 that the sealing structure 4 comprises asealing tongue 6 extending into or beyond the edge area 5 to form anaxial gas-tight covering of a media channel 8 formed in an adjacentbipolar plate 7 and located in the edge area 5. The fuel cell assemblyshown here has a total of four sealing tongues 6. Two of the sealingtongues 6 are arranged opposite one another on the shorter edge 9 a ofthe membrane electrode assembly 2. The other two sealing tongues 6 arearranged on the long edge 9 b of the membrane electrode assembly 2opposite one another and offset from one another. In the present case,the sealing tongues 6 all have a rectangular shape. However, polygonalshapes of the sealing tongues are possible, as are rounded sealingtongues 6.

The sealing structure 4 and the sealing tongues 6 are designed to bedimensionally stable with regard to a compressive and/or tensile stressacting axially on them. It can also be seen that the sealing tongues 6extend beyond the edge area 5. However, it is also possible that one ormore of the sealing tongues 6 only extend into the edge area 5, but notcompletely cover it or protrude laterally beyond it.

It can also be seen that the sealing structure 4 has a sealing edge 10sealing the membrane electrode assembly 2 laterally. The sealing lineformed by the sealing edge 10 seals the membrane electrode assembly 2against the lateral escape of media.

The sealing tongue 6 of the fuel cell assembly on the left side coversthe left media channels 8 of the first bipolar plate 7 a axially in agas-tight manner. The right sealing tongue 6 of the fuel cell assemblycovers the right media channels 8 of the first bipolar plate 7 a axiallyin a gastight manner. In other words, the left sealing tongue 6 isformed as a first inlet sealing tongue 6 a for axially gas-tightcovering of the first media inlet channel 8 a on the left. Accordingly,the right sealing tongue 6 is formed as a first outlet sealing tongue 6b for an axial gas-tight covering of the right first media outletchannel 8 b. The sealing tongues 6 provided at the long edge 17 a of thebipolar plate 7 a are resting on the composite layer 15. They can besubdivided into a second inlet sealing tongue 6 c and a second outletsealing tongue 6 d.

A plastic or a plastic blend can be used as the material of thecomposite layer 15, which may have a lower thermal stability than theplastic or plastic blend of the sealing structure 4 or the sealingtongues 6. Thus, during a hot pressing process, the sealing tongues 6can sink into the composite layer 15 and fuse with it, the sealingtongues 6 maintaining their dimensional stability. In other words, themelting point of the material of the sealing structure 4 is above themelting point of the material of the composite layer 15.

In the central area, that is to say where the active area 3 is located,the outer contour of the sealing structure 4 of the fuel cell assemblyis adapted to the inner contour specified by the composite layer 15.Here, the portions free of sealing tongues of the sealing structure 4form contact points, contact lines 18 or contact surfaces with thecomposite layer 15, to achieve a sealing function.

FIG. 7, section VII-VII of FIG. 6, shows a non-compressed sectionalillustration of the partial unit cell 11. It can be seen that the firstsealing tongues 6 a, 6 b protrude from the composite layer 15 and formprotrusions 19 at the same. In doing so, the necessary sealing in thelateral direction is achieved. Here, too, the illustration selected isnot to be understood to be true to scale. The thicknesses of theindividual layers may vary, such as after a bonding operation or joiningoperation (e.g., hot pressing operation), after which it may appear oract as a single common layer. The area of the recess 16 located betweenthe inlet sealing tongue 6 a and the channels 8 is then minimized insuch a way that the inlet sealing tongues 6 a axially cover the channels8. A medium can be supplied to the membrane electrode assembly 2laterally and in the stacking direction below the first inlet sealingtongue 8 a. Partially consumed medium can then leave the unit cell 11 ofthe fuel cell stack 12 laterally and in the stacking direction below thefirst outlet sealing tongue 8 b.

In FIG. 8, a connecting layer 20 is applied to the first inlet sealingtongue 6 a and to the first outlet sealing tongue 6 b, which is to beunderstood to be a further joining layer. The composite layer 15 and theconnecting layer 20 ensure a secure connection between a first bipolarplate 7 a and a second bipolar plate 7 b in the stacking direction. Thecomposite layer 15 forms overlaps 21 with the connecting layer 20 insuch a way that the two layers have a contact surface in the stackingdirection. This ensures a sealing function. The overlaps 21 can be seenin more detail in FIG. 9, section IX-IX of FIG. 8. Here also, it shows anon-compressed state, not to scale, which is intended to clarify thestacked assembly of the individual layers.

A second bipolar plate 7 b can now be applied to the composite layer 15and the connecting layer 20 connected thereto to complete the unit cell11. This can be seen in FIG. 10. The first bipolar plate 7 a and thesecond bipolar plate 7 b can be joined by means of the joining layers insuch a way that a unit cell 11 made of first bipolar plate 7 a, the fuelcell assembly and second bipolar plate 7 b is formed and that isprovided with not more than slight protrusions. However, the individuallayers of the unit cell 11 are connected without edges or without offsetin the stacking direction.

Like the first bipolar plate 7 a, second bipolar plate 7 b shown in FIG.10 and FIG. 11, also has a flow field 13 c for conducting a coolingmedium on its side facing away from the membrane electrode assembly 2.Said flow field 13 c is located substantially in the active area 3. Itis fluidly connected with coolant inlet channels 8 e and with coolantoutlet channels 8 f. In addition, the second bipolar plate 7 b alsoincludes recessed areas which form the flange receptacles 26.

However, at its side facing the membrane electrode assembly 2, thesecond bipolar plate 7 b has one or more second media outlet channels 8c and one or more second media outlet channels 8 d (FIG. 11). It alsocomprises a second flow field 13 b that is fluidly connected to thesecond media inlet channel 8 c and to the second medium outlet channel 8d, through which one of the reaction media can be supplied to themembrane electrode assembly 2.

FIG. 12 illustrates a fuel cell stack 12 formed of several unit cells11. This fuel cell stack 12 has the advantage, that the bipolar plate 7,compared to known bipolar plates, can be configured to have smallerdimensions so that the manufacturing costs of the fuel cell stack 12 arereduced. In the present case, the bipolar plates 7 are basicallyrectangular in shape, the present fuel cell devices not only beingdependent on a rectangular shape of the bipolar plates 7, but can alsobe used without limitation in any shapes with, for example, round orcurved lines. It is important in this context that a plurality of flangereceptacles 26 formed to be running parallel to the stacking directionarm is present at the fuel cell stack 12 at which flange receptacles 26the media ducts 22 can be fixed 22.

FIG. 13 shows a sectional view taken along section XIII-XIII of FIG. 10through a fuel cell stack 12. It can be seen that, after the joining orhot pressing operation, the compound layer 15 touches or contacts boththe first bipolar plate 7 a and the second bipolar plate 7 b, whereinthe bipolar plates 7 are connected or joined to each other by thecomposite layer 15. It can also be seen that the second media inletchannels 8 c are covered axially in a gas-tight manner by the secondinlet sealing tongues 6 c extending into or over the edge area 5. Thisalso applies to the second bipolar plate 7 b on the opposite side, wheresecond outlet sealing tongues 6 d extending into or beyond the edge area5 are provided for covering the second media outlet channels 8 c axiallyin a gas-tight manner. In FIG. 13 it can also be seen that a secondreaction medium is conducted to the membrane electrode assembly 2laterally and in the stacking direction above the sealing structure 4.Accordingly, the partially consumed second reaction medium is alsoconducted in the stacking direction above the sealing structure 4laterally out of the unit cells 11 or out of the fuel cell stack 12.

The second bipolar plate 7 b of a first unit cell 11, together with afirst bipolar plate 7 a of a further unit cell 11, then forms thecomplete channel cross section for the passage of the cooling medium. Inother words, they then also form the coolant inlet channels 8 e and thecoolant outlet channels 8 f The second bipolar plate 7 b of the firstunit cell 11 and the first bipolar plate 7 a of the further unit cell 11can also be joined with each other with a joining agent or joiningmedium. Alternatively, a generatively manufactured integralconfiguration of the adjacent bipolar plates 7 is possible.

FIG. 14 shows a sectional view taken along section XIV-XIV of FIG. 10through a fuel cell stack 12. It can be seen that, in the stackingdirection, the second bipolar plate 7 a is applied to the connectinglayer 20 and the composite layer 15. It can also be seen that a firstreaction medium is conducted to the membrane electrode assembly 2 in thestacking direction below the sealing structure 4. In this case, thefirst media inlet channels 8 a are covered axially in a gas-tight mannerby the first inlet sealing tongues 6 a. A first reaction medium issupplied laterally or in a lateral direction with respect to thestacking direction. Correspondingly, the partially consumed firstreaction medium is also conducted out laterally or sideward from theunit cell 11 or from the fuel cell stack 12 in the stacking directionbelow the sealing structure 4.

FIG. 15 shows a sectional view through the fuel cell device 1 accordingto FIG. 1 b, which substantially corresponds to the plan view of theunit cells 11 according to FIG. 10. It can be seen that the media ducts22 formed as a functional component 35 with their duct flanges 24 a, 24b are now inserted into the flange receptacles 26.

The media ducts 22 shown here have a duct crosspiece 23 which connectsthe two terminal duct flanges 24 a, 24 b with each other. Each of theduct flanges 24 a, 24 b is received in one of the flange receptacles 26extending parallel to the stacking direction, of the fuel cell stack 12.The open side of the media ducts 22 faces the fuel cell stack 12, sothat a medium flowing through them can laterally enter the unit cells12. The media ducts 22 are substantially rectangular in cross section,however, a different shape is possible. The media channels 22 may beformed from a dimensionally stable, plastic.

FIG. 16 shows a different shape of the media ducts 22 formed as afunctional component 35, a cross section through the fuel cell stack 12of FIG. 1b being shown here. Here, the media ducts 22 are formed to besemi-circular or C-shaped, so that the duct flanges 24 a, 24 b areconnected directly to each other, dispensing with a duct crosspiece 23.

From the detailed view according to FIG. 17 it can be seen that, in thepresent case, the media ducts 22 are formed to be elastically resilient.In doing so, the duct flanges 24 a, 24 b are held in an outwardlydirected pre-load in the flange receptacles 26 of the fuel cell stack12. A restoring force (indicated by force arrows 29) is effective andthe media ducts 22 are secured within the flange receptacles 26 due tothis restoring force. In addition, the duct flanges 24 a, 24 b areadditionally secured due to the pressure of a medium flowing in themedia ducts 22. This medium also brings about an outwardly directedforce, which—added together with the restoring force—lead to an evenstronger connection between the media ducts 22 and the fuel cell stack12.

Alternatively or in addition, the flange receptacles 26 can also beformed in accordance with the detail shown in FIG. 18. Here, the flangereceptacles 26 have an undercut 27 in which a duct member 28 formed orarranged on the duct flange 24 a, 24 b can be received. Within theflange receptacle 26—opposite the undercut 27—an inclined insertionsurface 30 is formed, which facilitates the insertion of the duct flange24 a, 24 b into the flange receptacle 26. The insertion surface 30 isinclined both with respect to the long edge 17 a and with respect to theshort edge 17 b of the bipolar plate 7. The insertion surface 30 changesto a lateral contact surface 31 which is oriented parallel to the plateedge and which predetermines and/or limits the depth of penetration ofthe duct flanges 24 a, 24 b into the flange receptacle 26. Starting fromthe contact surface 31, flange receptacle 26 then changes to agroove-shaped contact surface 32 forming the undercut 27.

While in the example of FIG. 17, the duct member 28 is formed integrallywith the duct flange 24 a, 24 b, the duct member 28 is shaped of adifferent material than the duct flange 24 a, 24 b in the example ofFIG. 19. This other material can, for example, be an additional sealingmaterial in order to additionally ensure the leakproofness of the fuelcell stack 12.

The present configuration of the fuel cell device 1 allows apositionally accurate assembly of the media ducts 22 on the fuel cellstack 12. The fixing of the duct flanges 24 a, 24 b within the flangereceptacles 26 of the fuel cell stack 12 by means of the force-fittingand/or firmly bonded and/or interlocking coupling withstands a largeforce directed away from the fuel cell stack 12, which force is exertedby pressure of the media flowing in media ducts 22. The media ducts 22are characterized by their excellent self-locking function, wherein theproduction complexity is reduced due to the integration of thefunctional component 35.

In general, in the following claims, the terms used should not beconstrued to limit the claims to the specific embodiments disclosed inthe specification and the claims, but should be construed to include allpossible embodiments along with the full scope of equivalents to whichsuch claims are entitled.

1. A fuel cell device, comprising: a fuel cell stack including aplurality of unit cells stacked one above the other in a stackingdirection, each unit cell having one or more media channels and amembrane electrode assembly that comprises a cathode, an anode, and amembrane arranged between the cathode and the anode; and a media ductrunning substantially parallel to the stacking direction, which mediaduct is connected or can be connected to the fuel cell stack in order toconduct a medium into or out of the media channels of the unit cells ofthe fuel cell stack substantially laterally to the stacking direction,wherein the media duct is formed as a functional component or such afunctional component is integrated therein, which is designed topre-treat the medium before the medium enters the media channels or topost-treat the medium after the medium has exited the media channels,wherein the fuel cell stack has flange receptacles which are formed toreceive in each case a duct flange of the media duct, and wherein themedia duct is elastically resilient in such a way that the duct flangesare held under a pre-load in the flange receptacles in a self-lockingmanner.
 2. The fuel cell device according to claim 1, wherein thefunctional component is selected from the group consisting of: ahumidifier, an ion exchanger, an ion trap, a particle filter, an airfilter, and a water separator.
 3. The fuel cell device according toclaim 1, wherein several the media ducts are provided, wherein the mediaducts are formed as a first media supply for supplying air, as a firstmedia discharge for discharging at least partially consumed air, as asecond media supply for supplying a fuel, and as a second mediadischarge for discharging at least partially consumed fuel.
 4. The fuelcell device according to claim 3, wherein the first media supply isformed as a humidifier or such a humidifier integrated therein.
 5. Thefuel cell device according to claim 3, wherein the first media dischargeis formed as an air filter or such an air filter is integrated therein.6. The fuel cell device according to claim 3, wherein the second mediasupply is formed as a particle filter or such a particle filter isintegrated therein.
 7. The fuel cell device according to claim 3,wherein the second media discharge is formed as a water separator orsuch a water separator is integrated therein.
 8. The fuel cell deviceaccording to claim 3, wherein the media ducts are subdivided into acoolant supply and a coolant discharge.
 9. The fuel cell deviceaccording to claim 8, wherein the coolant supply is formed as an ionexchanger or such an ion exchanger is integrated therein.
 10. (canceled)